1. Field of the Invention
The present invention relates to a flash emission method and a flash emission apparatus, and more particularly to a flash emission method and a flash emission apparatus that take an image with a flash emitted (flash image) prior to main emission and an image without a flash emitted (non-flash image) prior to main emission and determine the amount of emission light for the main emission based on those flash and non-flash images taken.
2. Description of the Related Art
One of the known techniques of determining the amount of flash emission light for the main emission (main photographing) is so-called “CCD light adjusting” (for example, Japanese Patent Application Laid-Open No. 2008-79143). In the CCD light adjusting technique, an image is taken with a flash pre-emitted in a predetermined amount (flash image) and another image is taken without a flash emitted (non-flash image) so that the amount of emission light for the main emission is determined based on the flash and non-flash images (the amount of emission light for the main emission is determined based on the amount of pre-emission light that influences the image by comparing the flash image and the non-flash image).
As a method for photographing a moving body, Japanese Patent Application Laid-Open No. H05-216087 discloses a method of finding a distance from a moving body, and if the distance from the moving body is short, photographing the moving body with a low aperture and a flash emitted.
When the amount of flash emission light is determined using the CCD light adjusting technique, two images of the flash image and the non-flash image are required. A drawback of the technique is that it cannot calculate the proper amount of emission light from the images if a moving body is taken in the angle of view or if the object is moving during the image capturing as the two images are taken serially. Especially, the drawback is that an excessively bright image or an excessively dark image is taken if a light source (neon lamp or the like) is in the background or if an image is taken as backlit since they significantly affect the image capturing.